NAME
DBIx::Lookup::Field - Create a lookup hash from a database table
VERSION
version 2.101420
SYNOPSIS
use DBI;
use DBIx::Lookup::Field qw(dbi_lookup_field);
my $dbh = DBI->connect('...', '...', '...');
my $inst_id = dbi_lookup_field(
DBH => $dbh,
TABLE => 'institution',
KEY => 'name',
VALUE => 'id',
);
print "Inst_A has id ", $inst_id->{Inst_A};
DESCRIPTION
This module provides a way to construct a hash from a database table.
This is useful for the situation where you have to perform many lookups
of a field by using a key from the same table. If, for example, a table
has an id field and a name field and you often have to look up the name
by its id, it might be wasteful to issue many separate SQL queries.
Having the two fields as a hash speeds up processing, although at the
expense of memory.
The functions can be exported individually or with the ":all" tag.
FUNCTIONS
dbi_lookup_field()
This function creates a hash from two fields in a database table on a
DBI connection. One field acts as the hash key, the other acts as the
hash value. It expects a parameter hash and returns a reference to the
lookup hash.
The following parameters are accepted. Parameters can be required or
optional. If a required parameter isn't given, an exception is raised
(i.e., it dies).
DBH The database handle through which to access the table from which to
create the lookup. Required.
TABLE
The name of the table that contains the key and value fields.
Required.
KEY The field name of the field that is to act as the hash key.
Required.
VALUE
The field name of the field that is to act as the hash value.
Required.
WHERE
A SQL 'WHERE' clause with which to restrict the 'SELECT' statement
that is used to create the hash. Optional.
dbi_lookup_field_with_reverse()
This function takes the same parameters as "dbi_lookup_field()" but in
addition to the lookup hash, it also returns a reversed hash where you
can lookup the table keys by the table values.
my ($lookup, $reverse) = dbi_lookup_field_with_reverse(...);
Note that if a value occurs more than once, only one of the potential
keys will win (the one that occurs first in the lookup hash's key
order), so be warned.
INSTALLATION
See perlmodinstall for information and options on installing Perl
modules.
BUGS AND LIMITATIONS
No bugs have been reported.
Please report any bugs or feature requests through the web interface at
.
AVAILABILITY
The latest version of this module is available from the Comprehensive
Perl Archive Network (CPAN). Visit to find a
CPAN site near you, or see
.
The development version lives at
. Instead of sending
patches, please fork this project using the standard git and github
infrastructure.
AUTHOR
Marcel Gruenauer
COPYRIGHT AND LICENSE
This software is copyright (c) 2001 by Marcel Gruenauer.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.